This study is designed to determine the clinical efficacy and effects on prefrontal cortical functioning of a selective D1 receptor agonist, SK&F 38393, in schizophrenic patients. Because 20% of schizophrenics respond only minimally to standard neuroleptics, an because "negative symptoms" (apathy, poor social engagement, flat affect, and poor insight) are particularly treatment resistant, new treatment approaches are needed. Work from several areas of study has suggested that the prefrontal cortex is a source of these deficit symptoms, and that it functions abnormally in these patients. Particularly, work in this branch using regional cerebral blood flow (rCBF), SPECT, and acute treatment of schizophrenic patients with dopamine agonists, indicate that schizophrenic patients have impaired prefrontal functioning which may be amenable to treatment with dopamine agonists. This drug study is aimed both of determining clinical efficacy of SK&F 38393 in treating schizophrenic symptoms and at understanding the biological effects of a D1 agonist on the CNS. Clinical measurements include ratings of general psychiatric symptoms, negative symptoms, and abnormal movements. Biological measurements include collections of CSF and serum, and the use of SPECT with and without frontal cortex activation (Wisconsin Card Sort). Other methods of understanding the drugs effect on the frontal cortex include a neuropsychological battery and use of a social competency instrument.